1. Field of the Invention
The present invention relates to a marker for predicting gastric cancer prognosis, a composition and a kit for predicting gastric cancer prognosis comprising an agent for measuring the expression level thereof, and a method for predicting gastric cancer prognosis using the marker.
2. Description of the Related Art
In 2005, a total of 65,479 people, which is 26.7% of all deaths, died of cancer. Cancer which causes the most deaths is lung cancer, of which 28.4 patients per 100,000 populations died (21.1%), the next is gastric cancer of 22.6 patients (16.8%), liver cancer of 22.5 patients (16.7%), colorectal cancer of 12.5 patients (9.3%) in order. Gastric cancer is known as the factor that causes the second most deaths worldwide among the deaths caused by cancer.
The symptoms of gastric cancer show various aspects, ranging from no symptoms to severe pain. In addition, the symptoms of gastric cancer appear common digestive symptoms without any specific characteristics. In general, in the early stage of gastric cancer, most cases have no symptom, even if any, little as a little indigestion or upper abdominal discomfort, which causes most people to overlook and therefore can increase the mortality of gastric cancer.
Most of examination methods for gastric cancer up to the present have been physical ones. First is stomach X-ray, which includes double contrast method, compression x-ray, mucosagraphy, and the next is gastroscopy which increases the diagnostic yield by finding a very small lesion that does not appear in the X-ray inspection through inspection of the stomach with the naked eyes and allowing the stomach biopsy in a suspicious place. However, this method has the disadvantages of hygienic problem and patients suffering from the pain during the inspection. Therefore, in recent years, the researches for diagnosing gastric cancer by measuring the expression level of the marker genes that are specifically expressed in the stomach have been carried out, but the researches on genetic markers for predicting the prognosis of gastric cancer patients are relatively less.
The survival rate of patients with gastric cancer depends on the pathologic stage at the time of diagnosis. According to the data of Samsung Medical Center, the 5-year survival rate of patients with gastric cancer is as follows (Kim S et al., Int J Radiat Oncol Biol Phys 2005; 63:1279-85).
stage II: 76.2%, stage IIIA: 57.6%,
stage IIIB: 39.6%, stage IV: 26.3%
The results show that early detection of gastric cancer can contribute significantly to the increase of survival rate. However, since the gastric cancer which has been diagnosed with the same stage shows the difference in the prognosis according to the patient, the accurate prediction of the prognosis of gastric cancer as well as the early detection of gastric cancer are the most important factors for effective treatment of gastric cancer.
On the other hand, the diagnosis of gastric cancer, the doctor is set up to conduct the necessary inspections and to patients that are deemed the most appropriate treatment plan. There are methods for treatment of cancer such as surgery, endoscopic therapy, chemotherapy, and radiation therapy. The method for treatment is typically determined by considering the treatment for gastric cancer, gastric cancer of the size, location, and scope of, the patient's general health status, and many other factors.
In the case of the treatment of IB/II stage gastric cancer only with the surgery, it is known that approximately 30% of patients relapse within 5 years. In this case, since it is unable to predict in which patients the gastric cancer is recurrent, the different treatments are applied according to the doctor. Therefore, if the prognosis of gastric cancer patients can be accurately predicted, appropriate treatment methods, such as surgery or chemotherapy, can be determined based on the prognosis, which can contribute greatly to the survival of gastric cancer patients, and therefore the technique that can accurately predict the prognosis of gastric cancer patients is required.
Conventionally, anatomical observations (the degree of cancer cell invasion and the number of metastasized lymph nodes) have been used in order to predict the prognosis of gastric cancer patients, but there have been the possible intervention of physician's subjective judgment and the limitation of accurate prediction of the prognosis.
Under such a background, the present inventors, as the result of the researches for the method which can increase the survival rate of gastric cancer patients by predicting the gastric cancer prognosis accurately and determining the appropriate treatment direction according to the predicted prognosis, identified that the gastric cancer prognosis can be accurately predicted by identifying a marker for predicting the gastric cancer prognosis and measuring the expression level of the marker, to complete the present invention.